add calc app for debugging.

3 years ago · 133c4a9e6e
20 changed files with 1086 additions and 2 deletions
--- a/Avalonia.sln
+++ b/Avalonia.sln
@ -229,6 +229,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ControlCatalog.Blazor.Web",
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "ControlCatalog.Web", "samples\ControlCatalog.Web\ControlCatalog.Web.csproj", "{8B3E8405-DE18-4048-A459-9CA4AC3319A2}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Calc", "samples\Calc\Calc.csproj", "{5AE1651A-B97A-40F8-B094-646A9EDCE09A}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@ -539,6 +541,10 @@ Global
 		{8B3E8405-DE18-4048-A459-9CA4AC3319A2}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{8B3E8405-DE18-4048-A459-9CA4AC3319A2}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{8B3E8405-DE18-4048-A459-9CA4AC3319A2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{5AE1651A-B97A-40F8-B094-646A9EDCE09A}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{5AE1651A-B97A-40F8-B094-646A9EDCE09A}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{5AE1651A-B97A-40F8-B094-646A9EDCE09A}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{5AE1651A-B97A-40F8-B094-646A9EDCE09A}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@ -603,6 +609,7 @@ Global
 		{62D392C9-81CF-487F-92E8-598B2AF3FDCE} = {9B9E3891-2366-4253-A952-D08BCEB71098}
 		{6A710364-AE6D-40BD-968B-024311527AC2} = {9B9E3891-2366-4253-A952-D08BCEB71098}
 		{8B3E8405-DE18-4048-A459-9CA4AC3319A2} = {9B9E3891-2366-4253-A952-D08BCEB71098}
+		{5AE1651A-B97A-40F8-B094-646A9EDCE09A} = {9B9E3891-2366-4253-A952-D08BCEB71098}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {87366D66-1391-4D90-8999-95A620AD786A}
--- a/samples/Calc/App.axaml
+++ b/samples/Calc/App.axaml
@ -0,0 +1,18 @@
+<Application
+    x:Class="Calc.App"
+    xmlns="https://github.com/avaloniaui"
+    xmlns:local="using:Calc"
+    xmlns:themes="clr-namespace:Material.Styles.Themes;assembly=Material.Styles"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+    <Application.DataTemplates>
+        <local:ViewLocator />
+    </Application.DataTemplates>
+
+    <Application.Styles>
+        <themes:MaterialTheme
+            BaseTheme="Dark"
+            PrimaryColor="DeepPurple"
+            SecondaryColor="Lime" />
+        <StyleInclude Source="avares://Material.Icons.Avalonia/App.xaml" />
+    </Application.Styles>
+</Application>
--- a/samples/Calc/App.axaml.cs
+++ b/samples/Calc/App.axaml.cs
@ -0,0 +1,36 @@
+using Avalonia;
+using Avalonia.Controls.ApplicationLifetimes;
+using Avalonia.Markup.Xaml;
+using Calc.ViewModels;
+using Calc.Views;
+
+namespace Calc
+{
+    public partial class App : Application
+    {
+        public override void Initialize()
+        {
+            AvaloniaXamlLoader.Load(this);
+        }
+
+        public override void OnFrameworkInitializationCompleted()
+        {
+            if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
+            {
+                desktop.MainWindow = new MainWindow
+                {
+                    DataContext = new MainWindowViewModel()
+                };
+            }
+            else if (ApplicationLifetime is ISingleViewApplicationLifetime singleView)
+            {
+                singleView.MainView = new MainView
+                {
+                    DataContext = new MainWindowViewModel()
+                };
+            }
+
+            base.OnFrameworkInitializationCompleted();
+        }
+    }
+}
--- a/samples/Calc/Assets/avalonia-logo.ico
+++ b/samples/Calc/Assets/avalonia-logo.ico
--- a/samples/Calc/Calc.csproj
+++ b/samples/Calc/Calc.csproj
@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+    <PropertyGroup>
+        <TargetFramework>net7.0</TargetFramework>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+    <ItemGroup>
+        <AvaloniaResource Include="Assets\**" />
+        <ProjectReference Include="..\..\packages\Avalonia\Avalonia.csproj" />
+        <PackageReference Include="Material.Avalonia" Version="3.0.0-avalonia11-preview2" />
+        <PackageReference Include="Material.Icons.Avalonia" Version="1.2.0" />
+        <PackageReference Include="XamlNameReferenceGenerator" Version="1.3.4" />
+        <ProjectReference Include="..\..\src\Avalonia.ReactiveUI\Avalonia.ReactiveUI.csproj" />
+    </ItemGroup>
+
+  <Import Project="..\..\build\BuildTargets.targets" />
+</Project>
--- a/samples/Calc/Models/Calculation.cs
+++ b/samples/Calc/Models/Calculation.cs
@ -0,0 +1,29 @@
+using System.IO;
+
+namespace Calc.Models;
+
+public class Calculation
+{
+    private readonly double _firstValue;
+    private readonly double _secondValue;
+    private readonly Operator? _operator;
+
+    public Calculation(double firstValue, double secondValue, Operator? @operator)
+    {
+        _firstValue = firstValue;
+        _secondValue = secondValue;
+        _operator = @operator;
+    }
+
+    public double Calculate()
+    {
+        return _operator switch
+        {
+            Operator.Add => _firstValue + _secondValue,
+            Operator.Subtract => _firstValue - _secondValue,
+            Operator.Multiply => _firstValue * _secondValue,
+            Operator.Divide => _firstValue / _secondValue,
+            _ => throw new InvalidDataException("Operator not allowed")
+        };
+    }
+}
--- a/samples/Calc/Models/Calculator.cs
+++ b/samples/Calc/Models/Calculator.cs
@ -0,0 +1,112 @@
+using System;
+using System.Globalization;
+
+namespace Calc.Models;
+
+public static class Calculator
+{
+    public static string Calculate(string str)
+    {
+        var calculus = new MyStringBuilder(str);
+
+        var numberOfOpeningParentheses = calculus.Count('(');
+        var numberOfClosingParentheses = calculus.Count(')');
+        
+        if (numberOfOpeningParentheses != numberOfClosingParentheses)
+            return "Waiting until all parentheses are closed";
+        
+        CalculateParentheses(ref calculus);
+        CalculateNonParentheses(ref calculus);
+
+        return calculus.ToString();
+    }
+
+    private static Operator? CharToOperator(char? character)
+    {
+        return character switch
+        {
+            OperatorChar.Add => Operator.Add,
+            OperatorChar.Subtract => Operator.Subtract,
+            OperatorChar.Multiply => Operator.Multiply,
+            OperatorChar.Divide => Operator.Divide,
+            _ => null
+        };
+    }
+
+    private static void CalculateNonParentheses(ref MyStringBuilder calculus)
+    {
+        int indexOfOperator;
+        
+        // Search calculations with precedence first. When there isn't more, continue with the others
+        while ((indexOfOperator = calculus.IndexOfAny(OperatorChar.PrecedentOperators, 1)) > 0 ||
+               (indexOfOperator = calculus.IndexOfAny(OperatorChar.NonPrecedentOperators, 1)) > 0)
+        {
+            // ==== Find the first operand ==== //
+            var indexOfPreviousOperator = SetIndexOfPreviousOperator(calculus, indexOfOperator);
+            var stringOfFirstValue = calculus[(indexOfPreviousOperator + 1)..indexOfOperator];
+            var startIndexOfCalculation = indexOfPreviousOperator + 1;
+
+            // First value could be just the sign -, e.g. in --3
+            if (stringOfFirstValue.Length == 1 &&
+                OperatorChar.IsAnOperator(stringOfFirstValue[0]))
+            {
+                stringOfFirstValue = "0";
+                indexOfOperator--; // This way operator would be - and secondValue -3
+            }
+            
+            // ==== Find the second operand ==== //
+            // startIndex = indexOfOperator + 2 avoids to detect sign of second value as operator
+            var indexOfNextOperator = calculus.IndexOfAny(OperatorChar.Operators, indexOfOperator + 2);
+
+            if (indexOfNextOperator == -1) // Last calculation
+                indexOfNextOperator = calculus.Length;
+            
+            var stringOfSecondValue = calculus[(indexOfOperator + 1)..indexOfNextOperator];
+            var nextIndexAfterCalculation = indexOfNextOperator;
+
+            // ==== Construct the calculation ==== //
+            var firstValue = Convert.ToDouble(stringOfFirstValue);
+            var @operator = CharToOperator(calculus[indexOfOperator]);
+            var secondValue = Convert.ToDouble(stringOfSecondValue);
+
+            var calculation = new Calculation(firstValue, secondValue, @operator);
+            
+            // Replace calculation with its result
+            calculus.Replace(startIndexOfCalculation, nextIndexAfterCalculation,
+                Convert.ToString(calculation.Calculate(), CultureInfo.CurrentCulture));
+        }
+    }
+
+    private static void CalculateParentheses(ref MyStringBuilder calculus)
+    {
+        int indexOfOpeningParenthesis;
+        while ((indexOfOpeningParenthesis = calculus.LastIndexOf('(')) != -1)
+        {
+            var indexOfClosingParenthesis = calculus.IndexOf(')', indexOfOpeningParenthesis);
+            // Replace parentheses with its result
+            calculus.Replace(indexOfOpeningParenthesis, indexOfClosingParenthesis + 1,
+                Calculate(calculus[(indexOfOpeningParenthesis + 1)..indexOfClosingParenthesis]));
+        }
+    }
+
+    private static int SetIndexOfPreviousOperator(MyStringBuilder calculus, int indexOfOperator)
+    {
+        var indexOfPreviousOperator = calculus.LastIndexOfAny(OperatorChar.Operators, indexOfOperator - 1);
+        
+        // First calculation. There could not be an operator at the beginning, it must be a sign
+        if (indexOfPreviousOperator == 0)
+        {
+            indexOfPreviousOperator = -1;
+        }
+        // If the first value is negative and not the first calculation, an operator must be just before the index
+        // previously calculated as the indexOfPreviousOperator, e.g. in a+-b/c the - isn't previousOperator, it's +
+        else if (indexOfPreviousOperator > 0 &&
+                 calculus[indexOfPreviousOperator].Equals(OperatorChar.Subtract) && // minus sign
+                 OperatorChar.IsAnOperator(calculus[indexOfPreviousOperator - 1])) // previous index contains an operator
+        {
+            indexOfPreviousOperator--;
+        }
+        
+        return indexOfPreviousOperator;
+    }
+}
--- a/samples/Calc/Models/MyStringBuilder.cs
+++ b/samples/Calc/Models/MyStringBuilder.cs
@ -0,0 +1,159 @@
+using System;
+using System.Text;
+
+namespace Calc.Models;
+
+public sealed class MyStringBuilder
+{
+    private readonly StringBuilder _stringBuilder = new();
+
+    public int Length => _stringBuilder.Length;
+    
+    public char this[int index] => _stringBuilder[index];
+
+    public char this[Index index] => _stringBuilder[index];
+
+    public string this[Range range] {
+        get
+        {
+            var chain = new MyStringBuilder();
+            
+            for (var i = range.Start.Value; i < range.End.Value; i++)
+            {
+                chain.Append(this[i]);
+            }
+
+            return chain.ToString();
+        }
+    }
+
+    public MyStringBuilder(){}
+    
+    public MyStringBuilder(string s)
+    {
+        _stringBuilder.Append(s);
+    }
+
+    public override string ToString()
+    {
+        return _stringBuilder.ToString();
+    }
+
+    public MyStringBuilder Append<T>(T stuff)
+    {
+        _stringBuilder.Append(stuff);
+
+        return this;
+    }
+
+    public MyStringBuilder Clear()
+    {
+        _stringBuilder.Clear();
+
+        return this;
+    }
+
+    public int Count(char character)
+    {
+        char[] chars = { character };
+        return Count(chars);
+    }
+    
+    public int Count(char[] chars)
+    {
+        var count = 0;
+        var i = 0;
+
+        while (i < Length)
+        {
+            foreach (var character in chars)
+            {
+                if (this[i].Equals(character))
+                {
+                    count++;
+                    break;
+                }
+            }
+            i++;
+        }
+
+        return count;
+    }
+
+    public int IndexOf(char character, int startIndex = 0)
+    {
+        char[] chars = { character };
+        return IndexOfAny(chars, startIndex);
+    }
+
+    public int IndexOfAny(char[] chars, int startIndex = 0)
+    {
+        var i = startIndex;
+        
+        while (i >= 0 && i < Length)
+        {
+            foreach (var character in chars)
+            {
+                if (this[i].Equals(character))
+                    return i;
+            }
+            i++;
+        }
+
+        return -1;
+    }
+
+    public MyStringBuilder Insert<T>(int index, T stuff)
+    {
+        _stringBuilder.Insert(index, stuff);
+
+        return this;
+    }
+    
+    public int LastIndexOf(char character)
+    {
+        return LastIndexOf(character, Length - 1);
+    }
+    
+    public int LastIndexOf(char character, int startIndex)
+    {
+        char[] chars = { character };
+        return LastIndexOfAny(chars, startIndex);
+    }
+
+    public int LastIndexOfAny(char[] chars)
+    {
+        return LastIndexOfAny(chars, Length - 1);
+    }
+    
+    public int LastIndexOfAny(char[] chars, int startIndex)
+    {
+        var i = startIndex;
+        while (i >= 0 && i < Length)
+        {
+            foreach (var character in chars)
+            {
+                if (this[i].Equals(character))
+                    return i;
+            }
+            i--;
+        }
+
+        return -1;
+    }
+    
+    public MyStringBuilder Remove(int index, int length = 1)
+    {
+        _stringBuilder.Remove(index, length);
+
+        return this;
+    }
+
+    public MyStringBuilder Replace<T>(int startIndex, int endIndex, T replacement)
+    {
+        Remove(startIndex, endIndex - startIndex)
+            .Insert(startIndex, replacement);
+        
+        return this;
+    }
+}
--- a/samples/Calc/Models/Operator.cs
+++ b/samples/Calc/Models/Operator.cs
@ -0,0 +1,9 @@
+namespace Calc.Models;
+
+public enum Operator
+{
+    Add,
+    Subtract,
+    Multiply,
+    Divide
+}
--- a/samples/Calc/Models/OperatorChar.cs
+++ b/samples/Calc/Models/OperatorChar.cs
@ -0,0 +1,20 @@
+using System.Linq;
+
+namespace Calc.Models;
+
+public static class OperatorChar
+{
+    public const char Add = '+';
+    public const char Subtract = '-';
+    public const char Multiply = '*';
+    public const char Divide = '/';
+    
+    public static readonly char[] Operators = { Add, Subtract, Multiply, Divide };
+    public static readonly char[] PrecedentOperators = { Multiply, Divide };
+    public static readonly char[] NonPrecedentOperators = { Add, Subtract };
+
+    public static bool IsAnOperator(char character)
+    {
+        return Operators.Contains(character);
+    }
+}
--- a/samples/Calc/ViewLocator.cs
+++ b/samples/Calc/ViewLocator.cs
@ -0,0 +1,28 @@
+using System;
+using Avalonia.Controls;
+using Avalonia.Controls.Templates;
+using Calc.ViewModels;
+
+namespace Calc
+{
+    public class ViewLocator : IDataTemplate
+    {
+        public IControl Build(object data)
+        {
+            var name = data.GetType().FullName!.Replace("ViewModel", "View");
+            var type = Type.GetType(name);
+
+            if (type != null)
+            {
+                return (Control)Activator.CreateInstance(type)!;
+            }
+
+            return new TextBlock { Text = "Not Found: " + name };
+        }
+
+        public bool Match(object data)
+        {
+            return data is ViewModelBase;
+        }
+    }
+}
--- a/samples/Calc/ViewModels/MainWindowViewModel.cs
+++ b/samples/Calc/ViewModels/MainWindowViewModel.cs
@ -0,0 +1,207 @@
+using System;
+using System.Globalization;
+using System.IO;
+using System.Reactive;
+using Calc.Models;
+using ReactiveUI;
+
+namespace Calc.ViewModels
+{
+    public class MainWindowViewModel : ViewModelBase
+    {
+        private string _shownString = string.Empty;
+        private string _shownResult = string.Empty;
+        private int _numberOfOpeningParentheses;
+        private int _numberOfClosingParentheses;
+        
+        // Commands
+        public ReactiveCommand<Unit, Unit> AddDecimalSeparatorCommand { get; }
+        public ReactiveCommand<int, Unit> AddNumberCommand { get; }
+        public ReactiveCommand<Operator, Unit> AddOperatorCommand { get; }
+        public ReactiveCommand<Unit, Unit> AddParenthesisCommand { get; }
+        public ReactiveCommand<Unit, Unit> AlternateNegativePositiveCommand { get; }
+        public ReactiveCommand<Unit, Unit> ClearScreenCommand { get; }
+        public ReactiveCommand<Unit, Unit> DeleteLastCommand { get; }
+        public ReactiveCommand<Unit, Unit> PickResultCommand { get; }
+
+        public MainWindowViewModel()
+        {
+            AddDecimalSeparatorCommand = ReactiveCommand.Create(AddDecimalSeparator);
+            AddNumberCommand = ReactiveCommand.Create<int>(AddNumber);
+            AddOperatorCommand = ReactiveCommand.Create<Operator>(AddOperator);
+            AddParenthesisCommand = ReactiveCommand.Create(AddParenthesis);
+            AlternateNegativePositiveCommand = ReactiveCommand.Create(AlternateNegativePositive);
+            ClearScreenCommand = ReactiveCommand.Create(ClearScreen);
+            DeleteLastCommand = ReactiveCommand.Create(DeleteLast);
+            PickResultCommand = ReactiveCommand.Create(PickResult);
+        }
+
+        public string ShownString
+        {
+            get => _shownString;
+            set => this.RaiseAndSetIfChanged(ref _shownString, value);
+        }
+
+        public string ShownResult
+        {
+            get => _shownResult;
+            set => this.RaiseAndSetIfChanged(ref _shownResult, value);
+        }
+
+        private void AddDecimalSeparator()
+        {
+            if (CanDecimalSeparatorBePlaced())
+                ShownString += CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator;
+        }
+
+        private void AddNumber(int value)
+        {
+            ShownString += value;
+            Calculate(ShownString);
+        }
+
+        private void AddOperator(Operator @operator)
+        {
+            if (ShownString[^1].Equals('('))
+                return;
+            
+            if (IsLastInputAnOperator())
+                ShownString = ShownString[..^1];
+
+            ShownString += @operator switch
+            {
+                Operator.Add => OperatorChar.Add,
+                Operator.Subtract => OperatorChar.Subtract,
+                Operator.Multiply => OperatorChar.Multiply,
+                Operator.Divide => OperatorChar.Divide,
+                _ => throw new InvalidDataException("Operator not allowed")
+            };
+        }
+
+        private void AddParenthesis()
+        {
+            if (ShownString.Length == 0 || IsLastInputAnOperator() || ShownString[^1].Equals('('))
+            {
+                ShownString += "(";
+                _numberOfOpeningParentheses++;
+            }
+            else if (_numberOfClosingParentheses < _numberOfOpeningParentheses)
+            {
+                ShownString += ")";
+                _numberOfClosingParentheses++;
+                Calculate(ShownString);
+            }
+        }
+
+        private void AlternateNegativePositive()
+        {
+            var indexWhereSetOrUnsetSign = SetIndexWhereToSetOrUnsetSign();
+
+            if (ShownString.Length == 0 || ShownString[^1].Equals('('))
+                ShownString += OperatorChar.Subtract;
+            else
+            {
+                switch (ShownString[indexWhereSetOrUnsetSign])
+                {
+                    case OperatorChar.Subtract:
+                        if (indexWhereSetOrUnsetSign == 0 ||
+                            ShownString[indexWhereSetOrUnsetSign - 1].Equals('(') ||
+                            OperatorChar.IsAnOperator(ShownString[indexWhereSetOrUnsetSign - 1]))
+                            
+                            ShownString = ShownString.Remove(indexWhereSetOrUnsetSign, 1);
+                        else
+                            // Add -
+                            ShownString = ShownString[..indexWhereSetOrUnsetSign] +
+                                          OperatorChar.Subtract +
+                                          ShownString[indexWhereSetOrUnsetSign..];
+                        break;
+                    default:
+                        // Add -
+                        ShownString = ShownString[..indexWhereSetOrUnsetSign] +
+                                      OperatorChar.Subtract +
+                                      ShownString[indexWhereSetOrUnsetSign..];
+                        break;
+                }
+                
+                Calculate(ShownString);
+            }
+        }
+
+        private void Calculate(string calc)
+        {
+            ShownResult = Calculator.Calculate(calc);
+        }
+        
+        private bool CanDecimalSeparatorBePlaced()
+        {
+            var indexLastDecimalSeparator = ShownString.LastIndexOf(
+                CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator,
+                StringComparison.Ordinal);
+            var indexLastOperator = ShownString.LastIndexOfAny(OperatorChar.Operators);
+
+            if (indexLastDecimalSeparator == -1 && indexLastOperator == -1)
+                return true;
+            
+            return indexLastOperator > indexLastDecimalSeparator;
+        }
+
+        private void ClearScreen()
+        {
+            ShownString = string.Empty;
+            ShownResult = string.Empty;
+            _numberOfOpeningParentheses = 0;
+            _numberOfClosingParentheses = 0;
+        }
+
+        private void DeleteLast()
+        {
+            if (ShownString.Length == 1)
+            {
+                ClearScreen();
+                return;
+            }
+
+            // Update number of parentheses
+            switch (ShownString[^1])
+            {
+                case '(':
+                    _numberOfOpeningParentheses--;
+                    break;
+                case ')':
+                    _numberOfClosingParentheses--;
+                    break;
+            }
+            
+            ShownString = ShownString[..^1];
+            Calculate(IsLastInputAnOperator() ? ShownString[..^1] : ShownString);
+        }
+
+        private bool IsLastInputAnOperator()
+        {
+            return OperatorChar.IsAnOperator(ShownString[^1]);
+        }
+        
+        private static int MaxOf(int number1, int number2)
+        {
+            return number1 > number2 ? number1 : number2;
+        }
+        
+        private void PickResult()
+        {
+            ShownString = ShownResult;
+            ShownResult = string.Empty;
+        }
+
+        private int SetIndexWhereToSetOrUnsetSign()
+        {
+            char[] nonSubstractOperators = { OperatorChar.Add, OperatorChar.Multiply, OperatorChar.Divide };
+            
+            var indexAfterLastNonSubstractOperator = ShownString.LastIndexOfAny(nonSubstractOperators) + 1;
+            var indexOfLastSubstractOperator = ShownString.LastIndexOf(OperatorChar.Subtract);
+            var indexAfterLastParenthesis = ShownString.LastIndexOf('(') + 1;
+            var indexLastOperator = MaxOf(indexAfterLastNonSubstractOperator, indexOfLastSubstractOperator);
+
+            return MaxOf(indexAfterLastParenthesis, indexLastOperator);
+        }
+    }
+}
--- a/samples/Calc/ViewModels/ViewModelBase.cs
+++ b/samples/Calc/ViewModels/ViewModelBase.cs
@ -0,0 +1,8 @@
+using ReactiveUI;
+
+namespace Calc.ViewModels
+{
+    public class ViewModelBase : ReactiveObject
+    {
+    }
+}
--- a/samples/Calc/Views/MainView.axaml
+++ b/samples/Calc/Views/MainView.axaml
@ -0,0 +1,377 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:material="using:Material.Icons.Avalonia"
+             xmlns:system="clr-namespace:System;assembly=System.Runtime"
+             xmlns:viewModels="clr-namespace:Calc.ViewModels"
+             MaxWidth="800" MaxHeight="500" HorizontalAlignment="Stretch" VerticalAlignment="Stretch"
+             xmlns:m="using:Calc.Models"
+             mc:Ignorable="d" 
+             x:Class="Calc.Views.MainView"
+             x:DataType="viewModels:MainWindowViewModel"
+             x:CompileBindings="False">
+    <UserControl.Styles>
+        <Style Selector="Button">
+            <Setter Property="Margin" Value="5" />
+        </Style>
+        <Style Selector="Button TextBlock">
+            <Setter Property="FontSize" Value="20" />
+        </Style>
+        <Style Selector="TextBlock.screen">
+            <Setter Property="Background" Value="#2f2a2c" />
+            <Setter Property="Margin" Value="5" />
+            <Setter Property="FontSize" Value="30" />
+            <Setter Property="MinHeight" Value="35" />
+            <Setter Property="TextAlignment" Value="Right" />
+            <Setter Property="Foreground" Value="#ddffffff" />
+        </Style>
+    </UserControl.Styles>
+    <UserControl.KeyBindings>
+        <!--  0  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D0">
+            <KeyBinding.CommandParameter>
+                <system:Int32>0</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad0">
+            <KeyBinding.CommandParameter>
+                <system:Int32>0</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  1  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D1">
+            <KeyBinding.CommandParameter>
+                <system:Int32>1</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad1">
+            <KeyBinding.CommandParameter>
+                <system:Int32>1</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  2  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D2">
+            <KeyBinding.CommandParameter>
+                <system:Int32>2</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad2">
+            <KeyBinding.CommandParameter>
+                <system:Int32>2</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  3  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D3">
+            <KeyBinding.CommandParameter>
+                <system:Int32>3</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad3">
+            <KeyBinding.CommandParameter>
+                <system:Int32>3</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  4  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D4">
+            <KeyBinding.CommandParameter>
+                <system:Int32>4</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad4">
+            <KeyBinding.CommandParameter>
+                <system:Int32>4</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  5  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D5">
+            <KeyBinding.CommandParameter>
+                <system:Int32>5</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad5">
+            <KeyBinding.CommandParameter>
+                <system:Int32>5</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  6  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D6">
+            <KeyBinding.CommandParameter>
+                <system:Int32>6</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad6">
+            <KeyBinding.CommandParameter>
+                <system:Int32>6</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  7  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D7">
+            <KeyBinding.CommandParameter>
+                <system:Int32>7</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad7">
+            <KeyBinding.CommandParameter>
+                <system:Int32>7</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  8  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D8">
+            <KeyBinding.CommandParameter>
+                <system:Int32>8</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad8">
+            <KeyBinding.CommandParameter>
+                <system:Int32>8</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  9  -->
+        <KeyBinding Command="{Binding AddNumber}" Gesture="D9">
+            <KeyBinding.CommandParameter>
+                <system:Int32>9</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddNumber}" Gesture="NumPad9">
+            <KeyBinding.CommandParameter>
+                <system:Int32>9</system:Int32>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  +  -->
+        <KeyBinding Command="{Binding AddOperatorCommand}" Gesture="Add">
+            <KeyBinding.CommandParameter>
+                <m:Operator>Add</m:Operator>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddOperatorCommand}" Gesture="OemPlus">
+            <KeyBinding.CommandParameter>
+                <m:Operator>Add</m:Operator>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  -  -->
+        <KeyBinding Command="{Binding AddOperatorCommand}" Gesture="Subtract">
+            <KeyBinding.CommandParameter>
+                <m:Operator>Subtract</m:Operator>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddOperatorCommand}" Gesture="OemMinus">
+            <KeyBinding.CommandParameter>
+                <m:Operator>Subtract</m:Operator>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  .  -->
+        <KeyBinding Command="{Binding AddDecimalSeparatorCommand}" Gesture="OemPeriod" />
+        <!--  +-  -->
+        <KeyBinding Command="{Binding AlternateNegativePositiveCommand}" Gesture="Alt+Subtract" />
+        <KeyBinding Command="{Binding AlternateNegativePositiveCommand}" Gesture="Alt+OemMinus" />
+        <!--  Backspace  -->
+        <KeyBinding Command="{Binding DeleteLastCommand}" Gesture="Back" />
+        <!--  Delete  -->
+        <KeyBinding Command="{Binding ClearScreenCommand}" Gesture="Escape" />
+        <KeyBinding Command="{Binding ClearScreenCommand}" Gesture="Delete" />
+        <!--  *  -->
+        <KeyBinding Command="{Binding AddOperatorCommand}" Gesture="Multiply">
+            <KeyBinding.CommandParameter>
+                <m:Operator>Multiply</m:Operator>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  /  -->
+        <KeyBinding Command="{Binding AddOperatorCommand}" Gesture="Divide">
+            <KeyBinding.CommandParameter>
+                <m:Operator>Divide</m:Operator>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <KeyBinding Command="{Binding AddOperatorCommand}" Gesture="Oem2">
+            <KeyBinding.CommandParameter>
+                <m:Operator>Divide</m:Operator>
+            </KeyBinding.CommandParameter>
+        </KeyBinding>
+        <!--  ()  -->
+        <KeyBinding Command="{Binding AddParenthesisCommand}" Gesture="OemOpenBrackets" />
+        <KeyBinding Command="{Binding AddParenthesisCommand}" Gesture="OemCloseBrackets" />
+        <!--  =  -->
+        <KeyBinding Command="{Binding PickResultCommand}" Gesture="Enter" />
+    </UserControl.KeyBindings>
+    <Grid Margin="5" RowDefinitions="Auto, Auto, *">
+        <!--  Screens  -->
+        <TextBlock
+            Classes="screen"
+            Grid.Row="0"
+            Text="{Binding ShownString}" />
+        <TextBlock
+            Classes="screen"
+            Grid.Row="1"
+            Text="{Binding ShownResult}" />
+        <!--  Keys  -->
+        <Grid
+            ColumnDefinitions="*,*,*,*,*"
+            Grid.Row="2"
+            RowDefinitions="*,*,*,*">
+            <!--  Numeric keys  -->
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="0"
+                Grid.Row="3">
+                <Button.CommandParameter>
+                    <system:Int32>0</system:Int32>
+                </Button.CommandParameter>
+                0
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="0"
+                Grid.Row="2">
+                <Button.CommandParameter>
+                    <system:Int32>1</system:Int32>
+                </Button.CommandParameter>
+                1
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="1"
+                Grid.Row="2">
+                <Button.CommandParameter>
+                    <system:Int32>2</system:Int32>
+                </Button.CommandParameter>
+                2
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="2"
+                Grid.Row="2">
+                <Button.CommandParameter>
+                    <system:Int32>3</system:Int32>
+                </Button.CommandParameter>
+                3
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="0"
+                Grid.Row="1">
+                <Button.CommandParameter>
+                    <system:Int32>4</system:Int32>
+                </Button.CommandParameter>
+                4
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="1"
+                Grid.Row="1">
+                <Button.CommandParameter>
+                    <system:Int32>5</system:Int32>
+                </Button.CommandParameter>
+                5
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="2"
+                Grid.Row="1">
+                <Button.CommandParameter>
+                    <system:Int32>6</system:Int32>
+                </Button.CommandParameter>
+                6
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="0"
+                Grid.Row="0">
+                <Button.CommandParameter>
+                    <system:Int32>7</system:Int32>
+                </Button.CommandParameter>
+                7
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="1"
+                Grid.Row="0">
+                <Button.CommandParameter>
+                    <system:Int32>8</system:Int32>
+                </Button.CommandParameter>
+                8
+            </Button>
+            <Button
+                Command="{Binding AddNumber}"
+                Grid.Column="2"
+                Grid.Row="0">
+                <Button.CommandParameter>
+                    <system:Int32>9</system:Int32>
+                </Button.CommandParameter>
+                9
+            </Button>
+            <!--  Non-numeric keys  -->
+            <Button
+                Command="{Binding AddDecimalSeparator}"
+                Grid.Column="1"
+                Grid.Row="3">
+                .
+            </Button>
+            <Button
+                Command="{Binding AlternateNegativePositive}"
+                Grid.Column="2"
+                Grid.Row="3">
+                +/-
+            </Button>
+            <Button
+                Command="{Binding DeleteLast}"
+                Grid.Column="3"
+                Grid.Row="0">
+                <material:MaterialIcon Kind="Backspace" />
+            </Button>
+            <Button
+                Command="{Binding ClearScreen}"
+                Grid.Column="4"
+                Grid.Row="0">
+                <material:MaterialIcon Kind="DeleteForever" />
+            </Button>
+            <Button
+                Command="{Binding AddOperator}"
+                Grid.Column="3"
+                Grid.Row="1">
+                <Button.CommandParameter>
+                    <m:Operator>Multiply</m:Operator>
+                </Button.CommandParameter>
+                <material:MaterialIcon Kind="Multiply" />
+            </Button>
+            <Button
+                Command="{Binding AddOperator}"
+                Grid.Column="4"
+                Grid.Row="1">
+                <Button.CommandParameter>
+                    <m:Operator>Divide</m:Operator>
+                </Button.CommandParameter>
+                <material:MaterialIcon Kind="Division" />
+            </Button>
+            <Button
+                Command="{Binding AddOperator}"
+                Grid.Column="3"
+                Grid.Row="2">
+                <Button.CommandParameter>
+                    <m:Operator>Add</m:Operator>
+                </Button.CommandParameter>
+                <material:MaterialIcon Kind="Add" />
+            </Button>
+            <Button
+                Command="{Binding AddOperator}"
+                Grid.Column="4"
+                Grid.Row="2">
+                <Button.CommandParameter>
+                    <m:Operator>Subtract</m:Operator>
+                </Button.CommandParameter>
+                <material:MaterialIcon Kind="Minus" />
+            </Button>
+            <Button
+                Command="{Binding AddParenthesis}"
+                Grid.Column="3"
+                Grid.Row="3">
+                <material:MaterialIcon Kind="CodeParentheses" />
+            </Button>
+            <Button
+                Command="{Binding PickResult}"
+                Grid.Column="4"
+                Grid.Row="3">
+                <material:MaterialIcon Kind="Equal" />
+            </Button>
+        </Grid>
+    </Grid>
+</UserControl>
--- a/samples/Calc/Views/MainView.axaml.cs
+++ b/samples/Calc/Views/MainView.axaml.cs
@ -0,0 +1,25 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace Calc.Views;
+
+public partial class MainView : UserControl
+{
+    public MainView()
+    {
+        InitializeComponent();
+    }
+
+    protected override void OnLoaded()
+    {
+        base.OnLoaded();
+        
+        Focus();
+    }
+
+    private void InitializeComponent()
+    {
+        AvaloniaXamlLoader.Load(this);
+    }
+}
--- a/samples/Calc/Views/MainWindow.axaml
+++ b/samples/Calc/Views/MainWindow.axaml
@ -0,0 +1,16 @@
+<Window
+    Height="500"
+    Icon="/Assets/avalonia-logo.ico"
+    Title="Calc"
+    Width="600"
+    d:DesignHeight="450"
+    d:DesignWidth="600"
+    mc:Ignorable="d"
+    x:Class="Calc.Views.MainWindow"
+    xmlns="https://github.com/avaloniaui"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:views="clr-namespace:Calc.Views" Focusable="False">
+    <views:MainView Focusable="True" />
+</Window>
--- a/samples/Calc/Views/MainWindow.axaml.cs
+++ b/samples/Calc/Views/MainWindow.axaml.cs
@ -0,0 +1,12 @@
+using Avalonia.Controls;
+
+namespace Calc.Views
+{
+    public partial class MainWindow : Window
+    {
+        public MainWindow()
+        {
+            InitializeComponent();
+        }
+    }
+}
--- a/samples/ControlCatalog.Blazor.Web/App.razor.cs
+++ b/samples/ControlCatalog.Blazor.Web/App.razor.cs
@ -2,12 +2,13 @@ using Avalonia;
 using Avalonia.Web.Blazor;

 namespace ControlCatalog.Blazor.Web;
+using Calc;

 public partial class App
 {
    protected override void OnParametersSet()
    {
-        AppBuilder.Configure<ControlCatalog.App>()
+        AppBuilder.Configure<Calc.App>()
            .UseBlazor()
            // .With(new SkiaOptions { CustomGpuFactory = null }) // uncomment to disable GPU/GL rendering
            .SetupWithSingleViewLifetime();
--- a/samples/ControlCatalog.Blazor.Web/ControlCatalog.Blazor.Web.csproj
+++ b/samples/ControlCatalog.Blazor.Web/ControlCatalog.Blazor.Web.csproj
@ -16,7 +16,9 @@
  <ItemGroup>
    <ProjectReference Include="..\..\src\Skia\Avalonia.Skia\Avalonia.Skia.csproj" />
    <ProjectReference Include="..\..\src\Web\Avalonia.Web.Blazor\Avalonia.Web.Blazor.csproj" />
-    <ProjectReference Include="..\ControlCatalog\ControlCatalog.csproj" />
+    <ProjectReference Include="..\Calc\Calc.csproj" />
+    <PackageReference Include="Material.Avalonia" Version="3.0.0-avalonia11-preview2" />
+    <PackageReference Include="Material.Icons.Avalonia" Version="1.2.0" />
  </ItemGroup>

  <Import Project="..\..\build\ReferenceCoreLibraries.props" />
--- a/src/Avalonia.Controls/Button.cs
+++ b/src/Avalonia.Controls/Button.cs
@ -347,6 +347,8 @@ namespace Avalonia.Controls

                if (!e.Handled && Command?.CanExecute(CommandParameter) == true)
                {
+                    Console.WriteLine("Executing");
+                    Console.WriteLine(Command.GetType().ToString());
                    Command.Execute(CommandParameter);
                    e.Handled = true;
                }